Direct Observation of Long-Chain Branches in a Low-Density Polyethylene

The properties of a polymer change significantly depending on the structure of the polymer chain, particularly, with branched structures, depending on the number of branches and the length of the branch.* However, the long-chain branch (LCB) structure of polyethylene was unclear, due particularly to the complex polymer structure and the limitations of its analysis methods.

In their study “Direct Observation of Long-Chain Branches in a Low-Density Polyethylene” Ken-ichi Shinohara, Masahiro Yanagisawa and Yuu Makida measured the chain length of LCBs and the distance between branch points of LDPE by atomic force microscopy.*

The article mentions the use of NanoWorld Ultra-Short Cantilevers (USC) for high speed atomic force microscopy ( AFM probe type USC-F1.2-k0.15 ) for the single-molecule imaging by atomic force microscopy .*

 Figure 1 from “Direct Observation of Long-Chain Branches in a Low-Density Polyethylene “ by K. Shinohara et al.: Direct measurement of LCB in a tubular LDPE (F200-0 fractionated). (A) AFM image of a single molecule of LDPE on mica in DMTS at 25 °C. X: 279 nm, Y: 209 nm, Z: 18 nm. (B) Length of each chain of LDPE. (C) A wire model of self-shrinking structure of polymer chain of LDPE. Main chain: red wire. LCB: black wire. The model was created to be one tenth of the length of the extended chain based on AFM observation (B), MD simulation (Fig. S1), and the molecular weight determined by SEC-MALLS-Visc experiments (see Fig. 2).
Figure 1 from “Direct Observation of Long-Chain Branches in a Low-Density Polyethylene “ by K. Shinohara et al.: Direct measurement of LCB in a tubular LDPE (F200-0 fractionated). (A) AFM image of a single molecule of LDPE on mica in DMTS at 25 °C. X: 279 nm, Y: 209 nm, Z: 18 nm. (B) Length of each chain of LDPE. (C) A wire model of self-shrinking structure of polymer chain of LDPE. Main chain: red wire. LCB: black wire. The model was created to be one tenth of the length of the extended chain based on AFM observation (B), MD simulation (Fig. S1), and the molecular weight determined by SEC-MALLS-Visc experiments (see Fig. 2).

*Ken-ichi Shinohara, Masahiro Yanagisawa, Yuu Makida
Direct Observation of Long-Chain Branches in a Low-Density Polyethylene
Nature Scientific Reportsvolume 9, Article number: 9791 (2019)
doi: https://doi.org/10.1038/s41598-019-46035-9

Please follow this external link for the full article: https://rdcu.be/bJY7S

Open Access: The article «Direct Observation of Long-Chain Branches in a Low-Density Polyethylene» by Ken-ichi Shinohara, Masahiro Yanagisawa and Yuu Makida is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Direct observation of dynamic interaction between a functional group in a single SBR chain and an inorganic matter surface

In the article  “Direct observation of dynamic interaction between a functional group in a single SBR chain and an inorganic matter surface” Ken-ichi Shinohara and Yuu Makida use atomic force microscopy (AFM) video imaging to closely investigate the behaviour of functionalized and unmodified styrene-butadiene rubber (SBR), as models for tire rubber, on mica surfaces.

“Using AFM video imaging, we tracked the behavior of individual SBR polymer chains on mica surfaces to reveal how polymer modification affects the interaction of SBR with mica surfaces. We measured the diffusion coefficients and spring constants of single SBR polymer chains for the first time, demonstrating that it is possible to parameterize the relationship between the molecular dynamic structure of a polymer and rubber properties of the vulcanized compound.”*

NanoWorld Ultra-Short Cantilevers (USC) for Fast-/High-Speed AFM  ( USC-F1.2-k0.15 ) were used

Figure 3 from “Direct observation of dynamic interaction between a functional group in a single SBR chain and an inorganic matter surface” by Ken-ichi Shinohara & Yuu Makida: (A) Single-molecule imaging of the structure of two isolated polymer chains of carboxyl-functionalized styrene-butadiene rubber (SBR) on mica under n-octylbenzene at 25 ± 1 °C (Movie S5). Snapshot AFM image of a fast-scanning atomic force microscopy (AFM) movie; X: 200 nm, Y: 150 nm, Z: 7.2 nm. Rate: 5.0 fps. (B) A snapshot of all-atom MD simulated structure of a single chain of carboxyl-functionalized SBR (CPK model) in n-octylbenzene as a solvent. Dynamic globular (ball-like) structures were formed partially in a SBR chain. The position of carboxyl group was indicated by an arrow. The backbone was displayed in purple. Solvent molecules are indicated by line model and hydrogen atoms are omitted for simplified to view. NanoWorld USC-F1.2-k0.15 AFM probes were used
Figure 3 from “Direct observation of dynamic interaction between a functional group in a single SBR chain and an inorganic matter surface” by Ken-ichi Shinohara & Yuu Makida: (A) Single-molecule imaging of the structure of two isolated polymer chains of carboxyl-functionalized styrene-butadiene rubber (SBR) on mica under n-octylbenzene at 25 ± 1 °C (Movie S5). Snapshot AFM image of a fast-scanning atomic force microscopy (AFM) movie; X: 200 nm, Y: 150 nm, Z: 7.2 nm. Rate: 5.0 fps. (B) A snapshot of all-atom MD simulated structure of a single chain of carboxyl-functionalized SBR (CPK model) in n-octylbenzene as a solvent. Dynamic globular (ball-like) structures were formed partially in a SBR chain. The position of carboxyl group was indicated by an arrow. The backbone was displayed in purple. Solvent molecules are indicated by line model and hydrogen atoms are omitted for simplified to view.

*Ken-ichi Shinohara & Yuu Makida
Direct observation of dynamic interaction between a functional group in a single SBR chain and an inorganic matter surface
Nature Scientific Reports, volume 8, Article number: 13982 (2018)
DOI: https://doi.org/10.1038/s41598-018-32382-6

For the full article please follow this external link: https://rdcu.be/bbERH

The article “Direct observation of dynamic interaction between a functional group in a single SBR chain and an inorganic matter surface” by Ken-ichi Shinohara & Yuu Makida is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

Effective gamma-ray sterilization and characterization of conductive polypyrrole biomaterials

“Conductive polymers, including polypyrrole (PPy), have been extensively explored to fabricate electrically conductive biomaterials for bioelectrodes and tissue engineering scaffolds. For their in vivo uses, a sterilization method without severe impairment of original material properties and performance is necessary. Gamma-ray radiation has been commonly applied for sterilization of medical products because of its simple and uniform sterilization without heat generation.[…]”*

In the article “Effective gamma-ray sterilization and characterization of conductive polypyrrole biomaterials” by Semin Kim et. al cited here, the authors describe the first study on gamma-ray sterilization of PPy bioelectrodes and its effects on their characteristics.

The surface topography and roughness of the PPy and γ-PPy electrodes were analyzed by atomic force microscopy. The experiments were performed using a NanoWorld Pointprobe® NCHR AFM probe. All images were acquired at a 0.3 Hz scan rate in tapping mode.

Figure 2 from “Effective gamma-ray sterilization and characterization of conductive polypyrrole biomaterials”: (a) Atomic force micrographs of PPy and γ-PPy samples irradiated with different doses of gamma-ray. (b) Average roughness (root mean square) of PPy and γ-PPy samples. NanoWorld Pointprobe NCHR AFM probes were used for the imaging.
Figure 2 from “Effective gamma-ray sterilization and characterization of conductive polypyrrole biomaterials”: (a) Atomic force micrographs of PPy and γ-PPy samples irradiated with different doses of gamma-ray. (b) Average roughness (root mean square) of PPy and γ-PPy samples.

*Semin Kim, Jin-Oh Jeong, Sanghun Lee, Jong-Seok Park, Hui-Jeong Gwon, Sung In Jeong, John George Hardy, Youn-Mook Lim, Jae Young Lee
Effective gamma-ray sterilization and characterization of conductive polypyrrole biomaterials
Nature Scientific Reports, volume 8, Article number: 3721 (2018)
DOI: https://doi.org/10.1038/s41598-018-22066-6

Please follow this external link for the full article: https://rdcu.be/bariF

Open Access: The article “Effective gamma-ray sterilization and characterization of conductive polypyrrole biomaterials” by Semin Kim et. al is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/.